Study Of Structure And Construction In Uranium-bearing Paleo-valley And Uranium Metallogenic Models In The Basaiqi Area,Erlian Basin

Erlian basin is an important uranium-producing basin in northern China.The main types of uranium deposits in the basin are paleo-valley sandstone types.The deposit is mainly concentrated in the Basaiqi uranium mineralization belt,and the deposits have been discovered by Basaiqi,Bayan Wula and Hadatu.The Saihan paleo-valley has the characteristics of long Valley,extensive connectivity,multi-deposit and multi-type.Basaiqi uranium mineralization belt is an important uranium mineralization belt in Erlian basin and North basin.It has special structural construction type,special uranium mineralization condition and many uranium deposits.At the same time,the sedimentary characteristics and stratigraphic division of the Neosahan Formation in the ancient Valley are not uniform,and the metallogenic hydrodynamics mechanism of the ancient Valley is lacking.Therefore,it is of great significance to study the structure and metallogenic model of the ancient Valley.In this paper,the regional Geological background of the development of the ancient Valley is introduced,the regional structure,strata,rock mass and uranium-bearing characteristics are introduced,and the regional tectonic evolution sequence is discussed.In the lower part of the old Valley,fan Delta-lake marshes were developed,dark mudstone developed,and formed favorable water layer with abundant organic matter.In the Late Cretaceous-Paleogene basin,a large denudation window was formed,and in the upper part of the Sehan Formation,the denudation window developed large-scale scuba-interlayer oxidation,which formed the anomaly of oxidation belt and uranium mineralization.There are three kinds of oxidation zones in the basin,which are scuba diving zone,scuba diving zone and interlayer zone.Uranium mineralization in the ancient Valley runs through the formation and evolution of the ancient Valley and the tectonic activities after the sedimentary period.The controlled elements are uranium source,palaeovalley sand body,postgenetic oxidation,reduction medium and postgenetic fluid.Its essence is the source area U⁴⁺activated.The uranium mineralization found in the ancient river valley mainly consists of the Bayanora deposit,the Sahan Gaobi deposit,the Hadatou deposit and the Chor ancient mining area.Through the study of the hydrodynamics of uranium mineralization in the ancient Valley,there are two types of uranium mineralization in the ancient Valley:?1?the reduction medium of sand body and the Redox mineralization of deep hydrocarbon reduction.?2?Mixed unloading and mineralization of oxygen-bearing fluid with different salinity.The main metallogenic types of Bayanora deposit are the ancient Valley scuba-interlayer oxidation zone,while those of Saihangaobi are the ancient Valley scuba oxidation zone and those of Hadatu deposit.The metallogenic model of the typical deposit is established by the structural construction of the ancient Valley and the study of the typical deposit model,which are Hadatu,Saihan and Bayanoulal respectively.The reasons and relationships of sandstone-type uranium deposits in the ancient Valley are explained by stratigraphic contrast,tectonic construction,metallogenic model and hydrodynamics of uranium mineralization.